Highly selective receiver circuit



Nov. 25, 1952 NQWAK 2,619,588

HIGHLY SELECTIVE RECEIVER CIRCUIT Filed May 15, 1949 Inventor Ia)" 0ll/aii Patented Nov. 25, 1952 OFFICE HIGHLY SELECTIVE RECEIVER CIRCUIT Karl Nowak, Vienna, Austria Application May 13, 1949, Serial No. 93,021 In Austria May 7, 1948 3 Claims.

This invention relates to a device for improving the selectivity in a receiving system, wherein regenerative feed back and degenerative feed back is applied in a reciprocal manner.

The invention consists in that the windings of both coils for producing regenerative and degenerative feed back, as well as the collecting or antenna coil, and the input circuit coil, are arranged and mounted on the same core.

In m developed device of improved selectivity wherein regenerative feed back and reciprocally applied degenerative feed back are used, some disadvantages have been found which are eliminated by this invention. Substantial improvement in the effect of the arrangement is obtained according to this invention wherein both the coil for regenerative feed back and the coil for degenerative feed back are mounted together with the coil of the grid circuit and the collecting coil, in that undesirable phase shifting of the currents flowing through the regenerative and degenerative coils, respectively, are substantially eliminated. Furthermore, it has been found that the efliciency of the arrangement may further be improved by reducing the number of turns of the grid-circuit-coil. According to the invention, the number of turns should be less than half the number of turns of the coil which produces the regenerative feed back, preferably less than onequarter, but even better, a fifth to a tenth of that number of turns. As far as the degenerative feedback coil is concerned, I came to the conclusion by theoretical reasoning that the number of turns of this coil should be as high as possible in order to yield optimum selectivity. However, it was found from experience that the number of turns of the degenerative feed back coil should be less than that of the regenerative feed back coil, preferably having approximately half or a quarter to a third of the turns of the latter.

Accordingly, it is the object of the invention to provide an improved circuit for receiving and amplifying electrical oscillations with higher selectivity.

It is a further object to provide an improved circuit arrangement for receiving and amplifying electrical oscillations having improved selectivity characteristics in which regenerative, degenerative, and antenna coils are mounted on the same core.

Another purpose of the invention is to provide an improved circuit arrangement for high selectivity reception of electromagnetic oscillations wherein the number of turns of the grid circuit and degeneration coils is less than the number of turns in the regeneration coil.

These objects and advantages will become apparent from a detailed consideration of the discussion given below in which the drawing illustrates a circuit embodying the principles of the invention.

Referring to the drawing, numerals 2 and 4 denominate the inductance and the condenser, respectively, of the regenerating circuit which is connected in series with the degenerative feed back coil 6. Both are inductively coupled to and act upon coil 8 of the input circuit of tube l 0.

The incoming signals are impressed from the collecting or antenna, coil l2 upon both the input circuit coil 8 and the inductance 2. The circuit is completed by a variable condenser 14 which connects the parallel resonant circuit I6 with the anode l8 of tube l8, and by radio frequency choke 20. According to the illustrated arrangement, an improved selectivity is obtained due to the frequency responsive voltage shift between resonant circuit [6 and degenerative feed back coil 6, as well as the mutual action upon coil 8. According to the invention, coils 2, 6, 8 and [2, as well as coil 22, from which the received energy can be taken oil, are mounted on a common support, preferably having a magnetic core. As an example, only the number of turns which may be given to the different coils are:

Coil 2 to turns Coil 8 10 to 30 turns, but preferably 15 Coil 6 20 to '70 turns, but preferably 40 Coil 22 50 to turns Aperiodical reception, which sometimes occurred when condenser M was adjusted so as to reduce the degree of regeneration and the turns of the grid coil 8 were high, could be eliminalted by the afore-mentioned form of the grid C01.

Instead of using coil 22, the received energy may be taken off in any suitable manner, for instance, by means of a condenser which is to be connected to the anode 8 of tube 2 and which may be connected to the grid circuit of the following stage.

Having described my invention, I claim:

1. A device for receiving electromagnetic oscillations with improved selectivity comprising a tube having at least a plate, a cathode, and a grid, a parallel tuned circuit comprising a regenerative coil and a condenser, and a degenerative coil being connected in series between the plate and cathode, a grid coil connected between said grid and said cathode, and an antenna coil, said grid coil, said antennacoil, said degenerative coil and said regenerative coil being wound on a common core, the number of turns of said grid coil being less than one quarter of the number of turns in said regenerative coil said regenerative and degenerative coils being energized simultaneously.

2. A device for receiving electromagnetic oscillations with improved selectivity comprising a tube having at least a plate, a cathode, and a grid, a parallel tuned circuit comprising a regenerative coil and a condenser, and a degenerative coil being connected in series between the plate and cathode, a grid coil connected between said grid and said cathode, and an antenna coil, said grid coil, said antenna coil, said degenerative coil and said regenerative coil being wound on a common core, the antenna coil being physically located between the regenerative coil and the grid coil on the common core said regenerative and degenerative coils being energized simultaneously.

3. A device for receiving electromagnetic oscillations with improved selectivity comprising a tube having at least a plate, a cathode, and a grid,

a parallel tuned circuit comprising regenerative coil and a condenser, and a degenerative coil be- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,591,660 Cory July 6, 926 2,125,982 Belleville Aug. 9, 1938 2,135,234 Fill Nov. 1, 1938 2,138,330 Thompson Nov. 29, 1938 2,141,573 Vogt Dec. 27, 1938 2,268,672 Plebanski Jan. 6, 1942 Taylor et a1 Aug. 17, 1948 

